The NASA Twins Study: A multidimensional analysis of a year-long human spaceflight

Abstract

To understand the health impact of long-duration spaceflight, one identical twin astronaut was monitored before, during, and after a 1-year mission onboard the International Space Station; his twin served as a genetically matched ground control. Longitudinal assessments identified spaceflight-specific changes, including decreased body mass, telomere elongation, genome instability, carotid artery distension and increased intima-media thickness, altered ocular structure, transcriptional and metabolic changes, DNA methylation changes in immune and oxidative stress–related pathways, gastrointestinal microbiota alterations, and some cognitive decline postflight. Although average telomere length, global gene expression, and microbiome changes returned to near preflight levels within 6 months after return to Earth, increased numbers of short telomeres were observed and expression of some genes was still disrupted. These multiomic, molecular, physiological, and behavioral datasets provide a valuable roadmap of the putative health risks for future human spaceflight.

Findings from recent studies by the Japan Aerospace Exploration Agency examining musculoskeletal atrophy in space and on Earth

“…Alteration of the gene expression pattern and cell morphology within the periosteum after loading suggests that these skeletal stem cells sense loading stimuli and remodeling 63 – 65 . In addition, mitochondrial function is likely to be affected by microgravity 24 , 37 , 66 , and the role of mitochondrial energy production mediated by oxidative phosphorylation in skeletal muscle stem cells (SMSCs) has been investigated. SMSCs are normally cell-cycle arrested but differentiate to generate myocytes upon muscle damage, and along with self-renewing SMSCs form new myofibers.…”

Ultrafast time-resolved x-ray absorption spectroscopy of ionized urea and its dimer through ab initio nonadiabatic dynamics

“…The response of biological matter to ionizing radiation is of fundamental interest to many fields, ranging from radiation oncology, 1 x-ray diffraction imaging, 2 and human space flight. 3 The dynamics in a molecule that are triggered by the formation of deep valence holes, i.e., by ionization beyond the highest occupied molecular orbital (HOMO), are of particular relevance for highly energetic ionizing radiation. Deep valence holes can be caused either by the direct interaction with extreme ultraviolet light or by secondary ionizations, e.g., by photoelectrons or Auger electrons following core-level ionization.…”

Gravitational Influence on Human Living Systems and the Evolution of Species on Earth

“…Since those initial evaluations, scientific progress has led to the advancement of physical examination in spaceflight. An interesting example was the NASA "Twins Study" [19]. This study was based on the very genuine idea, to investigate the effects of spaceflight in two identical twins, where the first is bound to Earth and the second remains in space for one year.…”

“…This study was based on the very genuine idea, to investigate the effects of spaceflight in two identical twins, where the first is bound to Earth and the second remains in space for one year. Yet, the idea moved further on by using all available biomedical technologies, which included simple hematological and biochemical analysis, transcriptomic analysis, epigenomic, immunophenotype, metabolomics, microbiomics, proteomics, physiology and telomeric analysis [19]. The study showed that Earth-bound physiology and spaceflight physiology differ, and it has been apparent that microgravity affects the magnitude of the human physiology and not only isolated physiological systems.…”

“…Post-flight orthostatic intolerance, cardiac atrophy and heart rhythm disturbances are some of the indications proving that microgravity affects the human cardiovascular system [25]. NASA demonstrated that mean arterial pressure is reduced in the case of longterm exposure to microgravity [19]. Is the evolution of mammalian blood pressure affected by gravity?…”